The present invention relates to a self-propelled upright vacuum cleaner comprising a unique HEPA-rated air filtration system. The present invention also relates to a self-propelled upright vacuum cleaner having a thermal cut-off circuit, a novel air routing configuration within the unit, and numerous other improvements and features.
There is an increasing emphasis upon the cleanliness of air discharged from vacuum cleaners. Prior artisans have attempted to provide secondary filters for vacuum cleaner exhaust air streams. Although satisfactory in most respects, most known secondary filtering configurations are difficult to design and incorporate within the vacuum cleaner, thereby increasing the complexity, manufacturing timer and cost of the unit. Furthermore, for assemblies employing replaceable filter elements, there is often considerable difficulty in replacing the element, particularly if it is located within the vacuum cleaner. Accordingly, there is a need for a vacuum cleaner comprising a secondary filtering assembly that overcomes the problems of the prior art. It would be particularly desirable to provide a vacuum cleaner with an easily replaceable filter element in combination with a sealed air path so that all air exiting the vacuum cleaner unit traveled through the filter prior to exiting the vacuum cleaner.
Air leaks from a vacuum cleaner unit, such as leakage of the exhaust stream around the motor housing into the environment, not only introduce particulates and contaminants into the outside environment and thus bypass any secondary filter if so provided, but also decrease the overall efficiency of the unit. Thus, there is a need for a vacuum cleaner providing an improved internal air routing configuration which prevents or at least significantly minimizes exhaust air leaks in and around the lower enclosure, and particularly around the motor housing.
It is desirable to provide a sensor and electrical circuit to stop operation of the vacuum cleaner motor in the event that the temperature of the motor exceeds a predetermined temperature. Heating of the motor typically results from a blocked or plugged filter, or from one or more objects interfering with the operation of the rotating brush or floor element. Prior artisans have incorporated temperature sensors and motor switching circuits in vacuum cleaners. However, as far as is known, none of the known sensors and switching circuits utilized in vacuum cleaners provide an automatic reset feature. That is, all known vacuum cleaners with on board temperature sensors may be started immediately after the sensor sufficiently cools. Although satisfactory in most respects, this configuration still enables electrical power to be applied to the motor. This may result in damage to the motor, in the event the motor is bound or otherwise locked. Accordingly, there is a need for an improved temperature sensing and motor interlock circuit whereby a reset operation is performed to ensure that electrical power is not inadvertently directed to a locked motor.
Self-propelled vacuum cleaners are known. However, much of the design and engineering efforts directed to such units are focused upon the drive assembly and vacuuming function. There remains an opportunity to improve other aspects of self propelled vacuum cleaners such as their noise level, electrical safety considerations, life of components such as the motor bearings, connections for an accessory hose, and configuration of the operator handle.
The present invention achieves all the foregoing objectives and provides in a first aspect, a vacuum cleaner comprising a housing and a base unit pivotally attached to each other, a motor and motor housing disposed within the base unit, a drive assembly also disposed within the base unit and selectively coupled to the motor, a nested wand releasably retained along the exterior of the housing, a lower air conduit extending between the base unit and a lower end of the wand, and an upper air conduit extending between an upper end of the wand and a suction chamber defined within the housing.
In another aspect, the present invention provides a vacuum cleaner comprising a lower base unit, an upper pivotable enclosure for housing a filter bag, a motor disposed within the lower base unit, a power cord and associated electrical conductors defining an electrical power circuit to the motor, and a thermal cutoff assembly including a temperature sensor disposed proximate to the motor for measuring the temperature of the motor, the thermal cutoff assembly including a switching element in the electrical power circuit that opens upon the temperature sensor sensing a temperature greater than a predetermined temperature setpoint.
In yet another embodiment, the present invention provides a vacuum cleaner comprising a lower base unit, an upper enclosure for retaining a filter bag, the upper enclosure defining a suction chamber, and exhaust chamber, and an exhaust opening providing access from the exterior of the upper enclosure to the exhaust chamber, a motor and fan assembly disposed within the upper enclosure and in airflow communication between the suction chamber and the exhaust chamber, and a detachable filter assembly that releasably engages the upper enclosure at or near the exhaust opening.
In yet another aspect, the present invention provides a vacuum cleaner comprising a lower base enclosure, an upper enclosure having internal walls dividing the upper enclosure into a suction chamber, an exhaust chamber, and a motor chamber, a motor and fan assembly disposed in a shroud which resides in the motor chamber, an air intake duct extending between the suction chamber and the shroud. The air intake duct engages either or both the suction chamber and the shroud along an unsealed interface.
According to a further aspect of this invention a motor and transmission module selectively powers a base drive wheel and at least the motor of the module is encased in a shroud. The shroud is connected by an exhaust passageway to the air flow path leading ultimately to the final filter.